jam marks ?

[Link]

Something my lil mind has been wondering?

When you chamber a dummy round and get lil square marks on the ogive from the lands.

How much jam do you have? The width of the land? If so how much on a 14 twist 6 mm?

Could you measure the square to get jam#?

If you have good concentricity, Shouldn't the marks be equal around the ogive? If not what does that tell you?

thanks

 

[Immike]

How deep you jam has alot to do with neck tension. I use wet moly bullets and I can only jam lightly and it pushes the bullet in the neck. A dry bullet with tight neck will go further. To measure the depth keep seating deeper until you don't get a mark. I close the bolt on a bullet 3 times to get my jam measurement then I use it to adjust from on the dies. I will do 3 bullets all the same to make sure I have a good jam #.
You may need to remove your ejector to get even marks.

Fixed my mistake, thanks preacher.

 

[Preacher]

It's also a good idea to remove the ejector when doing that...

 

[jonbearman]

The last posters are correct.Sinclair sells a tool and hornady makes a good tool for that as well.